STALK-EYED CRUSTACEA 461 



through which the eyes can be seen. The rostrum is 

 short and pointed. The internal antennae have the 

 peduncle short ; the first joint, flattened, has a spine on 

 the outside, and terminates in two flagella, the inner of 

 which has a tendency to bifurcate. The external antenna:^ 

 have a long flagellum, and a strong basal scale that has a 

 subapical point or sharp tooth. 



The first maxillipede is short and five-jointed. The 

 external maxillipede, pediform, five-jointed, has a short 

 slender external appendage. The first pair of legs 

 armed with pincers ; the sixth joint is large, the right, 

 being usually larger than the left, is of a more or less 

 abnormal form, especially in the male. The second 

 pair, slender, has minute pincers. The other legs 

 are simple, and terminate in short robust joints. The 

 last abdominal segment is broad and rounded ; the 

 outer plates of the swimming organ have a well marked 

 division. 



The gills are attached to the body wall, and to the 

 membrane between the body and the first joint of the 

 external maxillipede. 



Range, — In shallow and deep water of most seas ; one 

 has been found in fresh water in South- West Colorado — 

 Alp] tens nimtis. 



SYNorsis OF THE Species. 



A. A rostrum present, but no spines on front margin 

 of the carapace. 



a. The basal scale of the external antennae is as 

 long as the peduncle of the internal antennae. — {A. 

 armillatus.) 



b. The basal scale of the external antennae is longer 

 than the peduncle of the internal antennae. — (/J. bermu- 

 densis?) 



